According to what I read and experienced autobrightness in CM10 is not yet working properly. I have to enable light sensor filter, otherwise the brightness will only increase not decrease. It seems that using direct light sensor values is partly broken.

With the following setup, autobrightness works on my device:
- enable light sensor filter
- Set 'reset threshold' to something different than 'none'.
- enable 'Allow light decrease'
- don't modify the number of light leves (reset to default, if you changed the amount of light leves).

Screenshots can be found at this post: http://forum.xda-developers.com/show...3#post31124743 and later in the thread.
It has a safe kernel (emmc erase cap disabled), I patched the vibration, microphone, CRT-off animation, Wi-Fi Direct (P2P), added BLN, Wi-Fi MAC address changing and Voodoo Sound plus I added some tweaks, fixes and improvements.

Changelog:

06 August 2012: Pre-Pre-Alpha build (unreleased) with 2.6.36 kernel and GB drivers at this post

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